The present invention relates to a bearing arrangement comprising a shaft having a bearing journal and a needle bearing that is situated on the bearing journal and that has a cage and needle rollers accommodated therein, the bearing journal being provided with a hardened and precision-machined inner raceway for the needle rollers, the bearing journal springing back radially at least over part of its circumference relative to axial shoulders of adjacent shaft sections, and the axial shoulders acting as run-on surfaces for axial end faces of the cage fitted between the axial shoulders.
Such a bearing arrangement is known from the automotive engineering journal MTZ, 06/2008, pp. 528-524, in the form of an unbalanced shaft that is mounted by a needle bearing and that forms part of a mass balancing gearing of an internal combustion engine. High demands are made on the surface hardness and surface roughness of the inner raceway on the bearing journal that steps back radially there over its full circumference, in order to ensure an anti-friction bearing that is wear-resistant and is acoustically acceptable.
The heat input during local hardening of the shaft on the bearing journal—due as a rule to inductive heating of the bearing journal—can however cause an excessive heating of the axial shoulders immediately adjacent to the inner raceway, because the heat is inadequately conducted away due to the geometry of this bearing journal. This carries the risk of formation of stress cracks in the axial shoulders and in the adjacent shaft sections.
The present invention is based on the object of improving the construction of a bearing arrangement of the type described above with the least possible outlay in such a way that the heat treatment of the bearing journal can be carried out with reliable processing.